Create an alarm

An alarm activates when a metric passes a certain threshold. If you imagine a dashboard for your metrics, alarms are like red lights that light up when conditions change, for example, when there is a problem.

If you would like the platform to notify you when an alarm activates, create an Alert for it in Control view. Alerts are a group of one or more alarms. They are like a worker monitoring a group of alarms; when all the lights for the group are lit up, the alert is activated. Alerts can also trigger action plans to perform automated actions when their alarms activate. After you create an alert, create an action plan in Control view with the alert as a trigger.

You can create alarms for built-in VM metrics or scaling group metrics, as well as custom metrics created using the API for VMs, scaling groups, virtual appliances, and virtual datacenters.

You can push custom metrics for clone VMs but you cannot create alarms for cloned VMs that are part of a scaling group. This is because scaling groups have aggregate alarms that are associated with the base VM.

The label of the entity, which for VMs is shown in the list on the left

Entity icon

The icon that the platform displays in the UI for VMs and virtual appliances

Name

Name of the alarm with up to 128 characters. Alarm names must be unique for each metric

Description

Description of the alarm. Used together with the alarm name and VM name to identify the alarm, for example, when creating an alert

Metric

Select one of the metrics available for the VM

Metric unit

The unit of the metric. Read only

Metric description

The description of the metric. Read only

Dimension

When the metric has multiple dimensions, optionally select one or more dimensions. For example, if a VM has multiple hard disks, then the disk read bytes metric may have a dimension for each disk

Last datapoints in period

The number of datapoints that the platform will evaluate the metric during the elapsed time. The default value is All data points and the minimum value of the time period is 1 minute.

If you request the evaluation of an alarm more frequently than metric data is collected by the platform or sent by the provider, then the alarm will not activate.

The platform collects metrics data every 2 minutes by default, but this can be changed using a property for each plugin. For the default configuration, to ensure that an alarm will activate, it should be evaluated at intervals of greater than 2 minutes.

Moreover, each provider transmits metrics at different intervals, for example, with Amazon Basic monitoring, data is sent every 5 minutes, and with Advanced monitoring, every minute. For vCloud, data is available on consultation.

Note that for alarms with longer evaluation periods, for example, an average of 10 points over the last hour, the transmission and collection intervals will not affect the activation of the alarm.

Statistic

Statistic that the platform will use for evaluating the alarm, which can be: average, maximum, minimum, sum, count, dev

Formula

Operator that the platform will use for evaluation of the alarm, for example, greater than. Values can be: notequal, greaterthan, greaterthanorequalto, lessthan, lessthanorequalto, trendup, trenddown

Threshold

Value that the platform will evaluate the alarm against, if appropriate

Click Save

The platform will create the alarm for the metric. If you would like the platform to notify you when an alarm is triggered, create an Alert.

For a scaling group, an alarm on a metric of the VM in the base workload will receive input from the metrics of all VMs in the scaling group. This means the base workload and/or the clone VMs. So an alarm for a scaling group can activate, even if the base workload is not deployed.

Create alarms with the API

For API documentation about alarms on an entity, see the API documentation for the entity's resource. For example, for VMs, see VirtualMachinesResource.

Edit an alarm

When you edit an alarm, you cannot modify the metric or the entity.

When you edit an alarm, there is an extra field, "Active", that shows if the alarm is activated or not.

After you save the alarm, the platform will start to evaluate it again with new data when it receives the next set of metrics datapoints.

Delete an alarm

You can delete any alarm at any time, even if it is part of one or more alerts. The platform will not warn you that the alarm is used in an alert. However, you can check this in Control view. After you delete an alarm, you cannot recover it.